Citrix MetaFrame Application for Windows 1.8 Administrator's Manual page 63

Click Advanced in Async Transport Configuration to access the Advanced
Async Configuration dialog box. Use this dialog box to configure the following
options:
Option Description
Flow Control Specifies the type of flow control to use for the connection.
Hardware Specifies the hardware signals that indicate the receive buffer is full.
Flow Control
Software Flow Specifies the characters that stop and start data transmission.
Control
DTR State Specifies the state of the DTR signal (Always On or Always Off).
RTS State Specifies the state of the RTS signal (Always On or Always Off).
Parity Specifies the parity type.
Stop Specifies the number of stop bits per character.
Byte The number of data bits per character. Citrix ICA 3.0 requires
8 bits.
Click Test in Async Transport Configuration to access the Async Test dialog
box. Use this dialog box to test a serial port and any connected devices.
The name of the serial port and the configured baud rate are displayed at the top of
the window, along with a row of modem signal status indicators that show the
status of the DTR, RTS, CTS, DSR, DCD, and RI signals. The terminal window
allows you to send ASCII data to an attached device and displays any responses
from the device. Characters entered are not echoed unless the attached device
echoes them.